Braking system for a vehicle having hand and foot brake levers

ABSTRACT

A vehicle has a frame, a straddle seat, front right and left wheels, a rear wheel, a steering assembly, a motor, front right and left brakes, a rear brake, and an electronic brake control unit. The electronic brake control unit has a pump, a valve box, a first pressure sensor disposed in the valve box and an electronic controller. The electronic controller is electronically connected to the pump, and valves of the valve box for controlling their operation. A hand brake lever actuates a first master cylinder and thereby actuates the front brakes through the valve box. A foot brake lever actuates a second master cylinder and thereby actuates the rear brake through the valve box. A second pressure sensor is disposed externally of the valve box. The first and second pressure sensors sensing fluid pressure applied by the first and second master cylinders respectively.

CROSS-REFERENCE

The present application is claims priority to U.S. Provisional PatentApplication No. 62/598,797, filed Dec. 14, 2017, and U.S. ProvisionalPatent Application No. 62/711,138, filed Jul. 27, 2018, the entirety ofboth of which is incorporated herein by reference.

TECHNOLOGICAL FIELD

The present technology relates to a braking systems for vehicles havinghand and foot brake levers.

BACKGROUND

Many vehicles are now equipped with electronic brake control units thatcan control braking of the wheels at least partially independently ofbraking inputs from the driver of the vehicle. This is the case forexample of vehicles equipped with an anti-lock braking system (ABS).

Many vehicles such as automobiles have a single brake lever, which istypically a foot brake lever. Therefore, the brake pressure beingapplied as a result of the driver actuating the foot brake lever can beknown from a single pressure sensor. The electronic brake control unitcan use the pressure sensed from the single pressure sensor to assist incontrolling braking of all of the wheels.

Other vehicles, such as motorcycles and off-road all-terrain vehicles(ATV's), typically have a hand brake lever and a foot brake lever. Insome cases, actuating either one of the brake levers results in theactuation of all of the brakes, like when using the foot brake lever inan automobile. In such cases, an electronic brake control unit using asingle pressure sensor like the ones used in automobiles could be used.

In other cases, the hand lever actuates the front brakes and the footlever actuates the rear brakes. This is sometimes referred to as a splitbraking system. In such cases, an electronic brake control unit using asingle pressure sensor like the ones used in automobiles could not beused. Using such an electronic brake control unit in a split systemwould provide the braking assist functions (ABS for example) when theone of the hand brake lever and the foot brake lever with which thesingle pressure sensor is associated is actuated, but not when the otherone of the hand brake lever and the foot brake lever is actuated.

As the single pressure sensor of automotive electronic brake controlunits is typically provided inside the unit, one solution could be touse two electronic brake control units, one for the hand brake lever andone for the foot brake lever. However, such a solution is costly, bulkyand would result in very complex hydraulic connections between the brakelevers, the brake control units and the brakes.

Thus, there is a desire for a braking system including an electronicbrake control unit that can be used in a vehicle having hand and footbrake levers that form part of a split braking system.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

According to an aspect of the present technology, there is provided avehicle having a frame, a straddle seat mounted to the frame, a frontright wheel operatively connected to the frame, a front left wheeloperatively connected to the frame, a rear wheel operatively connectedto the frame, a steering assembly operatively connected to the frontleft and right wheels, a motor mounted to the frame for providing powerto at least one of the wheels, a front right brake operatively connectedto the front right wheel for braking the front right wheel, a front leftbrake operatively connected to the front left wheel for braking thefront left wheel, a rear brake operatively connected to the rear wheelfor braking the rear wheel, and an electronic brake control unit. Theelectronic brake control unit has a pump, a valve box fluidly connectedto the pump, a first pressure sensor and an electronic controller. Thevalve box has a first inlet, a first outlet fluidly connected to thefront right brake, a second outlet fluidly connected to the front leftbrake, a first valve selectively fluidly connecting the first inlet andthe pump with the first outlet, a second valve selectively fluidlyconnecting the first inlet and the pump with the second outlet, a secondinlet, a third outlet fluidly connected to the rear brake, and a thirdvalve selectively fluidly connecting the second inlet and the pump withthe third outlet. The first pressure sensor is disposed in the valve boxfor sensing a first fluid pressure between the first inlet and the firstand second valves. The electronic controller is electronically connectedto the pump, the first valve, the second valve and the third valve forcontrolling operation of the pump, the first valve, the second valve andthe third valve, and electronically connected to the first pressuresensor for receiving a first signal indicative of the first fluidpressure sensed by the first pressure sensor. The vehicle also has afirst master cylinder fluidly connected to the first inlet, a hand brakelever operatively connected to the first master cylinder for actuatingthe first master cylinder and thereby actuate the front right and leftbrakes through the valve box, a second master cylinder fluidly connectedto the second inlet, a foot brake lever operatively connected to thesecond master cylinder for actuating the second master cylinder andthereby actuate the rear brake through the valve box, and a secondpressure sensor disposed externally of the valve box. The secondpressure sensor senses fluid pressure between the second inlet and thesecond master cylinder. The second pressure sensor is electronicallyconnected to the electronic controller for sending a second signalindicative of the second fluid pressure sensed by the second pressuresensor. The electronic brake control unit selectively actuates the rearbrake in response to actuation of the first master cylinder by openingthe third valve and by actuating the pump. The electronic brake controlunit selectively actuates the front right and left brakes in response toactuation of the second master cylinder by opening the first and secondvalves and by actuating the pump.

In some embodiments of the present technology, the second pressuresensor is mounted to the second master cylinder.

In some embodiments of the present technology, the second pressuresensor is vertically higher than the foot brake lever.

In some embodiments of the present technology, the rear wheel is a rearright wheel. The vehicle also has a rear left wheel operativelyconnected to the frame. The rear brake is operatively connected to therear right and left wheels for braking the rear right and left wheels.

In some embodiments of the present technology, the rear wheel is a rearright wheel, and the rear brake is a rear right brake. The vehicle alsohas a rear left wheel operatively connected to the frame, and a rearleft brake operatively connected to the rear left wheel for braking therear left wheel. The valve box also has a fourth outlet fluidlyconnected to the rear left brake, and a fourth valve selectively fluidlyconnecting the second inlet and the pump with the fourth outlet. Theelectronic controller is electronically connected to the fourth valvefor controlling operation of the fourth valve. The foot brake lever isoperatively connected to the second master cylinder for actuating thesecond master cylinder and thereby actuate the rear right and leftbrakes through the valve box. The electronic brake control unitselectively actuates the rear left and right brakes in response toactuation of the first master cylinder by opening the third and fourthvalves and by actuating the pump.

In some embodiments of the present technology, the electronic brakecontrol unit selectively actuates the rear brake in response toactuation of the first master cylinder by opening the third valve and byactuating the pump only when the first pressure sensed by the firstpressure sensor is above a first pressure threshold. The electronicbrake control unit selectively actuating the front right and left brakesin response to actuation of the second master cylinder by opening thefirst and second valves and by actuating the pump only when the secondpressure sensed by the second pressure sensor is above a second pressurethreshold. The second pressure threshold is greater than the firstpressure threshold.

In some embodiments of the present technology, the first pressurethreshold is less than 0.5 psi.

In some embodiments of the present technology, the first pressurethreshold is 0 psi.

In some embodiments of the present technology, the second pressurethreshold is 5 psi.

In some embodiments of the present technology, when the electronic brakecontrol unit actuates the rear brake in response to actuation of thefirst master cylinder by opening the third valve and by actuating thepump: the first master cylinder applies a first front brake pressure tothe front right and left brakes, and the pump applies a first rear brakepressure to the rear brake. When the electronic brake control unitactuates the front right and left brakes in response to actuation of thesecond master cylinder by opening the first and second valves and byactuating the pump: the pump applies a second front brake pressure tothe front right and left brakes, and the second master cylinder appliesa second rear brake pressure to the rear brake. The first front brakepressure is greater than the first rear brake pressure.

In some embodiments of the present technology, the second rear brakepressure is greater than the second front brake pressure.

In some embodiments of the present technology, wherein, for equal firstfront brake pressure and second rear brake pressure, the first frontbrake pressure is greater than the second front brake pressure.

In some embodiments of the present technology, for equal first frontbrake pressure and second rear brake pressure, the second rear brakepressure is greater than the first rear brake pressure.

In some embodiments of the present technology, a front-to-rear brakingratio corresponds to the first front brake pressure divided by the firstrear brake pressure; a rear-to-front braking ratio correspond to thesecond rear brake pressure divided by the second front brake pressure;and the front-to-rear braking ratio is greater than the rear-to-frontbraking ratio.

In some embodiments of the present technology, a first inlet brake linefluidly connects the first master cylinder to the first inlet, a secondinlet brake line fluidly connects the second master cylinder to thesecond inlet, a first outlet brake line fluidly connects the front rightbrake to the first outlet, a second outlet brake line fluidly connectsthe front left brake to the second outlet, and third outlet brake linefluidly connects the rear brake to the third outlet.

In some embodiments of the present technology, the electronic controllercontrols operation of the first valve, the second valve and the thirdvalve by opening and closing of the first valve, the second valve andthe third valve cyclically for preventing locking of the front rightbrake, the front left brake and the rear brake respectively.

In some embodiments of the present technology, a brake fluid reservoiris spaced from and fluidly connected to the second master cylinder.

For purposes of this application, terms related to spatial orientationsuch as forwardly, rearward, upwardly, downwardly, left, and right, areas they would normally be understood by a driver of the vehicle sittingthereon in a normal riding position.

Embodiments of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Explanations and/or definitions of terms provided in the presentapplication take precedence over explanations and/or definitions ofthese terms that may be found in any documents incorporated herein byreference.

Additional and/or alternative features, aspects and advantages ofembodiments of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a left side elevation view of an all-terrain vehicle;

FIG. 2 is a perspective view, taken from a rear, right side, of left andright front suspensions, left and right rear suspensions, left and rightfront brakes, a rear brake, and steering components of the vehicle ofFIG. 1;

FIG. 3 is a right side elevation view of the components of FIG. 2;

FIG. 4 is a top plan view of the components of FIG. 2;

FIG. 5 is a bottom plan view of the components of FIG. 2;

FIG. 6 is a top plan view of an anti-lock braking system (ABS) assemblyof the vehicle of FIG. 1;

FIG. 7 is a perspective view taken from a rear, right side of the ABSassembly of FIG. 6;

FIG. 8 is a perspective view taken from a rear, right side of analternative embodiment of an ABS assembly of the vehicle of FIG. 1;

FIG. 9 is a right side view of a pressure sensor and a master cylinderof the foot brake lever of the ABS assembly of FIG. 6;

FIG. 10 is a close-up top view of the electronic brake control unit ofthe ABS assembly of FIG. 6;

FIG. 11 a schematic representation of the ABS assembly of FIG. 6; and

FIG. 12 a schematic representation of the ABS assembly of FIG. 8.

DETAILED DESCRIPTION

The present technology will be described with reference to afour-wheeled straddle-seat all-terrain vehicle (ATV) 9. However, it iscontemplated that aspects of the present technology could be used inother types of four-wheeled and three-wheeled vehicles having a straddleseat.

With reference to FIGS. 1 to 7, the ATV 9 has a front end 2 and a rearend 4 defined consistently with a forward travel direction of the ATV 9.The ATV 9 has a frame 12 to which is mounted an internal combustionengine 16 for powering the ATV 9. It is contemplated that the ATV 9 maybe powered by other types of motors, being for example powered by anelectric motor.

The ATV 9 has two front wheels 18 and two rear wheels 18. The wheels 18are operatively connected to the engine 16 via a transmission (notshown). Each of the four wheels 18 is provided with low-pressure balloontires adapted for off-road conditions and traversing rugged terrain.

As illustrated on FIG. 1, the ATV 9 also includes fairings 60 includinga front fascia 62 at the front end 2 of the ATV 9 and several sidepanels 64 extending over lateral sides of the ATV 9. A fender 66 isdisposed over each wheel 18 to protect the driver and/or passenger fromdirt, water and other debris being projected by the rotating wheels 18.The ATV 9 further includes a straddle seat 28 mounted to the frame 12for accommodating a driver of the ATV 9. Driver footrests 50 areprovided on either of the driver seat 28 and are disposed verticallylower than the driver seat 28 to support the driver's feet. Anotherstraddle seat 34 is provided behind the driver seat 28 to accommodate apassenger. A passenger footrest 52 is provided longitudinally rearwardof each of the left and right driver footrests 50. The passengerfootrests 52 are disposed slightly higher than the driver footrests 50and are designed to accommodate the feet of a passenger seated on thepassenger seat 34 which is disposed slightly vertically higher than thedriver seat 28. It is contemplated that the passenger seat 34 and thepassenger footrests 52 could be omitted.

The two front wheels 18 are suspended from the frame 12 by respectivefront suspension assemblies 24 while the two rear wheels 18 aresuspended from the frame 12 by respective rear suspension assemblies 26.

Each front suspension assembly 24 includes an upper A-arm 24 a, a lowerA-arm 24 b, a front shock absorber 24 c and a front coil spring 24 d.The front coil spring 24 d is mounted over the front shock absorber 24c. The front coil spring 24 d and the front shock absorber 24 c are bothpivotably connected at their lower ends to the upper A-arm 24 a and attheir upper ends to the frame 12. The upper and lower A-arms 24 a and 24b each have their inner end pivotably connected to the frame 12. Akingpin 85 (FIG. 4) is mounted to the outer ends of the upper and lowerA-arms 24 a and 24 b. Each front wheel 18 is rotationally connected toits corresponding kingpin 85. It is contemplated that the frontsuspension assemblies 24 could be of a different type.

Each rear suspension assembly 26 comprises a swing arm 26 a, a rearshock absorber 26 b and a rear coil spring 26 c. Each swing arm 26 a hasone end pivotably connected to the frame 12, about a pivot axis 54located in front of the rear wheels 18 and extending generally laterallywithin the frame 12, and an opposite end supporting the wheel shaft 86of its corresponding rear wheel 18. Each swing arm 26 a is connected atmid-length to a torsion bar 58 by links 59. The torsion bar 58 ismounted to the frame 12 via supports 56. For each rear suspensionassembly 26, the rear shock absorber 26 b and the rear coil spring 26 ceach have one end pivotally connected to the frame 12 and the other endpivotally connected to its corresponding swing arm 26 a. It iscontemplated that the rear suspension assemblies 26 could be of adifferent type.

A steering assembly 30 is rotationally supported by the frame 12 toenable a driver to steer the ATV 9. The steering assembly 30 includes ahandlebar 32 connected to a steering column 74 for actuating steeringlinkages 70 operably connected to the front left and right wheels 18. Apower steering electric motor 127 is mounted to the steering column 74.The power steering electric motor 127 is operatively connected to thesteering column 74 and to the left and right front wheels 18 via thesteering linkages 70.

The ATV 9 can be operated in rear-wheel drive mode or in four-wheeldrive mode. Its front end 2 includes a front differential 76 adapted toreceive, via a driveshaft 80 a torque from the engine 16. On each of itsleft and right sides, the front differential 76 is connected to an innerconstant velocity (CV) joint (not shown) connected to one end of arespective half shaft 78. Outer CV joints (not shown) are connected tothe outer ends of both half shaft 78. A wheel shaft 86 passing throughand supported by its corresponding kingpin 85 is connected to itscorresponding outer CV joint. A front wheel 18 and a front brake disc 82are mounted to each wheel shaft 86. Depending on riding conditions ofthe ATV 9, the front differential 76 may send unequal torque to the twofront wheels 18 so that the front left wheel 18 and the front rightwheel 18 may rotate at different speeds.

Front left and right brakes 88 each include a corresponding one of thebrake discs 82 and each further include a caliper 84 mounted on thecorresponding kingpin 85. The front left and right calipers 84 arerespectively connected to outlet brake lines 95L and 95R. Each caliper84 includes a pair of brake pads positioned on opposite sides of itsrespective brake disc 82. The front brakes 88 are actuated by actuatingthe calipers 84 by application of a fluid pressure in the outlet brakelines 95L and 95R, thereby causing the brake pads to apply pressure ontheir respective brake discs 82.

The ATV 9 includes a rear spool gear (not shown) enclosed within ahousing 97. An input shaft 100 of the spool gear 96 is operablyconnected to a shaft 101 by a universal joint 99. The shaft 101 isconnected by a universal joint 103 to the transmission to receive aninput torque from the engine 16. On each of its left and right sides,the spool gear 96 is connected to an inner CV joint (not shown)connected to an inner end of a respective half shaft 98. An outer CVjoint (not shown) is connected to an outer end of each half shaft 98.Two wheel shaft 104 pass through and are supported by the lower ends ofthe swing arms 26 a and are connected to the outer CV joints. The rearwheels 18 are mounted to the two wheel shaft 104. The spool geartransmits the torque received from the engine 16 to the rear left andright wheels 18 via the inner CV joints, the half shafts 98, the outerCV joints and the wheel shafts 104 such that the rear left and rightwheels 18 rotate together at the same speed.

The ATV 9 has a single rear brake 102. The rear brake 102 includes asingle brake disc 106 and a single caliper 108. The brake disc 106 ismounted to a wheel hub 107 that is mounted on the rear right wheel shaft104. Although the single rear brake 102 is located on the right-handside of the ATV 9, mounting the single rear brake 102 on the left-handside of the ATV 9 is also contemplated. The single caliper 108 issupported by the right swing arm 26 a. The single caliper 108 isconnected to an outlet brake line 116. The single caliper 108 includes apair of brake pads (not shown) positioned on opposite sides of the brakedisc 106. The rear brake 102 is actuated by actuating the caliper 108 byapplication of a fluid pressure in the outlet brake line 116, therebycausing the brake pads to apply pressure on the brake disc 106. The rearbrake 102 thus brakes both rear wheels 18.

In an alternative embodiment illustrated in FIG. 8, the ATV 9 has rearleft and right brakes 102. Both rear brakes have the same constructionas the rear brake 102 described above, and as such will not be describedagain in detail. In this embodiment, the spool gear is replaced by arear differential thereby allowing the rear left and right wheels 18 toturn at different speeds and allowing each rear brake 102 to brake itscorresponding rear wheel 18.

The ATV has a hand brake lever 90 connected to a front master cylinder92 used to actuate the front left and right brakes 88. The hand lever 90and the front master cylinder 92 are mounted on the left side of thehandlebar 32. The front master cylinder 92 can be directly filled withbrake fluid, but it is contemplated that the front master cylinder 92could be provided with a separate brake fluid reservoir. Actuating thehand brake lever 90 causes the front master cylinder 92 to transmit abrake pressure to an electronic brake control unit 124 via an inletbrake line 94 and from the electronic brake control 124 to the brakes 88via the outlet brake lines 95L, 95R as will be described in more detailbelow. When the hand brake lever 90 is actuated, a signal is sent via aconnector 93 for turning on brake lights (not shown).

The ATV also has a foot brake lever 110 connected to a rear mastercylinder 112. The foot brake lever 110 and the rear master cylinder 112are mounted on a bracket 114 supported by the lower portion of the frame12. The foot brake lever 110 is on a right side of the straddle seat 28.The rear master cylinder 112 receives brake fluid via a hose 118 from abrake fluid reservoir 120. As can be seen in the Figures, the brakefluid reservoir 120 is spaced from the rear master cylinder 122. Morespecifically, the brake fluid reservoir 120 is vertically higher thanthe rear master cylinder 112. Actuating the foot brake lever 110 causesthe rear master cylinder 112 to transmit a brake pressure to theelectronic brake control unit 124 via an inlet brake line 126 and fromthe electronic brake control 124 to the rear brake 102 via the outletbrake line 116 as will be described in more detail below. In theembodiment of FIG. 8, actuating the foot brake lever 110 causes the rearmaster cylinder 112 to transmit a brake pressure to the electronic brakecontrol unit 124 via the inlet brake line 126 and from the electronicbrake control 124 to the rear left and right brakes 102 via the outletbrake lines 116. When the foot brake lever 110 is actuated, a signal forturning on the brake lights is sent via a connector 111.

A bracket 125 mounted near the steering column 74 and the brakingcontrol unit 124 supports the various brake lines 94, 116 and 126. Twobrackets 129 mounted to the upper A-arms 24 a (see FIG. 4) support theleft and right outlet brake lines 95L, 95R.

As best seen in FIG. 10, the electronic brake control unit 124 includesa pump 154, an electronic controller 156 and a valve box 158. Theelectronic controller 156 and the pump 154 are energized by a battery122 mounted above the input shaft 100, the shaft 101 and the universaljoint 99. The battery 122 also energizes other electrical components ofthe ATV 9.

In the present embodiment, the power steering electric motor 127 and thebraking control unit 124 are mounted proximate to one another so thatthe pump 154 and the power steering electric motor 127 overlap at leastpartially in a vertical direction when viewed from a side of the ATV 9(i.e. as seen in FIG. 3).

The ATV 9 includes other components such as a throttle operator, a gearshifter, an air intake system, an exhaust system, radiators, headlights,and the like. As it is believed that these components would be readilyrecognized by one of ordinary skill in the art, further explanation anddescription of these components will not be provided herein.

Turning now to FIGS. 6, 9, 10 and 11, the braking system assembly of theATV 9 will be described in more detail. The braking system assemblyincludes the aforementioned brakes 88, 102, hand and foot brake levers90, 110, front and rear master cylinders 92, 112, brake fluid reservoir120, hose 118, brake lines 94, 95L, 95R, 116, 126 and braking controlunit 124. The braking system assembly also includes additionalcomponents described below. The braking system of the braking systemassembly of the present embodiment is an anti-lock braking system (ABS)designed to help prevent the wheels 18 from locking when braking as willbe described below.

With reference to FIG. 10, it can be seen that the valve box 158 of theelectronic brake control unit 124 is disposed laterally between the pump154 and the electronic controller 156, with the pump 154 being disposedon the left side of the valve box 58. It is contemplated that theelectronic brake control unit 124 could be oriented differently thanillustrated in the Figures.

The valve box 158 defines two inlets 160 a, 160 b on a left side thereofand four outlets 162 a, 162 b, 162 c, 162 d on a top thereof. It iscontemplated that the inlets 160 a, 160 b and outlets 162 a, 162 b, 162c, 162 d could be defined elsewhere on the valve box 158. With referenceto FIG. 10, the inlet 160 a is fluidly connected to the front mastercylinder 92 by the inlet brake line 94. The inlet 160 b is fluidlyconnected to the rear master cylinder 112 by the inlet brake line 126.The outlet 162 a is fluidly connected to the caliper 84 of the frontleft brake 88 by the outlet brake line 95L. The outlet 162 b is fluidlyconnected to the caliper 84 of the front right brake 88 by the outletbrake line 95R. The outlet 162 c is fluidly connected to the caliper 108of the rear brake 102 by the outlet brake line 116. In the presentembodiment, the outlet 162 d is plugged because it is not used, and assuch it is contemplated that the outlet 162 d could be omitted.

As can be seen in FIG. 11, the inlet 160 a fluidly communicates with theoutlets 162 a, 162 b and that the inlet 160 b fluidly communicates withthe outlet 162 c inside the valve box 158. As its name suggests, thevalve box 158 contains a number of valves 164 a, 164 b and 164 c. Thevalve 164 a selectively opens and closes the outlet 162 a and thereforeselectively communicates the inlet 160 a with the outlet 162 a. Thevalve 164 b selectively opens and closes the outlet 162 b and thereforeselectively communicates the inlet 160 a with the outlet 162 b. Thevalve 164 c selectively opens and closes the outlet 162 c and thereforeselectively communicates the inlet 160 b with the outlet 162 c. Thevalves 164 a, 164 b, 164 c are electronically connected to theelectronic controller 156 which controls their operation as will bedescribed below.

The pump 154 is electronically connected to the electronic controller156 which controls its operation as will be described below. The pump154, as can be seen in FIG. 11, is fluidly connected between the inlet160 a and the valve 164 a, between the inlet 160 a and the valve 164 b,and between the inlet 160 b and the valve 164 c. The valves 164 a, 164b, 164 c thus selectively fluidly communicate the pump 154 with theoutlets 162 a, 162 b, 162 c respectively. As such, by actuating the pump154 and opening the corresponding valve 164 a, 164 b, 164 c, theelectronic controller 158 can actuate a corresponding one of the brakes88, 102 completely independently or at least partially independently ofthe actuation of the hand and foot brake levers 90, 110.

As can also be seen in FIG. 11, a front pressure sensor 166 is disposedin the valve box 158. The front pressure sensor 166 senses the fluidpressure of the brake fluid between the inlet 160 a and the valves 164a, 164 b. The front pressure sensor 166 is electronically connected tothe electronic controller 158 to send a signal representative of thepressure it senses to the electronic controller 158.

As can be seen in FIG. 11, there is no pressure sensor inside the valvebox 158 between the inlet 160 b and the valve 164 c. Instead of beinginside the box 158, a rear pressure sensor 168 is provided externally ofthe valve box 158. The rear pressure sensor 168 senses the fluidpressure of the brake fluid between the rear master cylinder 112 thevalve 164 c. The rear pressure sensor 168 is electronically connected tothe electronic controller 158 to send a signal representative of thepressure it senses to the electronic controller 158. As best seen inFIG. 9, the rear pressure sensor 168 is mounted to the rear mastercylinder 112. More specifically, the rear pressure sensor 168 isdisposed between a fluid connector 170, and a connector 172, and thepressure sensor 168, and connectors 170, 172 are connected together toan outlet of the rear master cylinder 112. The fluid connector 170 isdisposed between the rear pressure sensor 168 and the rear mastercylinder 112. The fluid connector 170 connects the inlet brake line 126to the rear master cylinder 112. The connector 172 connects theconnector 111 to the rear master cylinder 112. The rear pressure sensor168 has a port 174 used to electronically connect the rear pressuresensor 168 to a port 176 (FIG. 10) of the electronic controller 156. Asbest seen in FIG. 3, the rear pressure sensor 168 is vertically higherthan the foot brake lever 110. Mounting the rear pressure sensor 168 tothe rear master cylinder 112 as described about provides a rigidconnection of the rear pressure sensor 168, thereby improving itsreadings, avoids the need of a split in the inlet brake line 126 whichwould otherwise be needed to install the rear pressure sensor 168,provides a location permitting easy installation and removal compared tothe front pressure sensor 166, and provides a location that isrelatively isolated from the elements by being shielded by the rightside panel 64 of the ATV 9. It is however contemplated that the rearpressure sensor 168 could be provided elsewhere on the ATV 9 to sensepressure inside the inlet brake line 126 anywhere between the rearmaster cylinder 112.

In the present embodiment, the driver of the ATV 9 can actuate the handbrake lever 90 or the foot brake lever 110 individually and theelectronic brake control unit 124 will cause all three brakes 88, 102 tobrake regardless of which brake lever 90, 110 is actuated as describedbelow.

When the driver actuates the hand brake lever 90, the front mastercylinder 92 transmits a first front brake pressure to the inlet 160 awhich is sensed by the front pressure sensor 166. The valves 162 a, 162b are opened and the first front brake pressure is applied to the frontleft and right brakes 88, thereby actuating the front brakes 88. Onlywhen the signal received by the electronic controller 156 from the frontpressure sensor 166 indicates a pressure that exceeds a first pressurethreshold, the electronic controller 156 opens the valve 162 c andactuates the pump 154 to apply a first rear brake pressure to the rearbrake 102, thereby actuating the rear brake 102. In some embodiments,the first pressure threshold is less than 0.5 psi. In the presentembodiment, the first pressure threshold is 0 psi, such that the valve162 c is opened and the pump 154 is actuated as soon as an increase inpressure is sensed by the front pressure sensor 166. The first frontbrake pressure applied by the front master cylinder 92 to the frontbrakes 88 is greater than the first rear brake pressure applied by thepump to the rear brake 102. The ratio corresponding to the first frontbrake pressure divided by the first rear brake pressure is known as thefront-to-rear braking ratio, and this ratio is greater than one (1.0) inresponse to the actuation of the hand brake lever 90.

When the driver actuates the foot brake lever 110, the rear mastercylinder 112 transmits a second rear brake pressure to the inlet 160 bwhich is sensed by the rear pressure sensor 168. The valve 162 c isopened and the second rear brake pressure is applied to the rear brake102, thereby actuating the rear brake 102. Only when the signal receivedby the electronic controller 156 from the rear pressure sensor 168indicates a pressure that exceeds a second pressure threshold, theelectronic controller 156 opens the valves 162 a, 162 b and actuates thepump 154 to apply a second front brake pressure to the front brakes 88,thereby actuating the front brakes 108. In the present embodiments, thesecond pressure threshold is less than 5 psi, but other values arecontemplated. The second pressure threshold (i.e. 5 psi) is greater thanthe first pressure threshold described above (i.e. less than 0.5 psi or0 psi) because the rear pressure sensor 168 is more likely to generate anoisy signal than the front pressure sensor 166 that is in the valve box158. Therefore, the higher pressure threshold helps ensure that thepressure signal sent by the rear pressure sensor 168 is indicative of apressure resulting of actuation of the rear master cylinder 112 by thefoot brake lever 110 and is not the result of a noisy signal. The secondrear brake pressure applied by the rear master cylinder 112 to the rearbrake 102 is greater than the second front brake pressure applied by thepump to the front brakes 88. The ratio corresponding to the second rearbrake pressure divided by the second front brake pressure is known asthe rear-to-front braking ratio, and this ratio is greater than one(1.0) in response to the actuation of the foot brake lever 110.

In the present embodiment, the front-to-rear braking ratio is greaterthan the rear-to-front braking ratio. Also, when comparing a firstscenario where the master cylinder 92 applies the first front brakepressure to the front brakes 88 and the pump 154 applies the first rearbrake pressure to the rear brake 102 to a second scenario where themaster cylinder 112 applies the second rear brake pressure to the rearbrake 102 and the pump 154 applies the second front brake pressure tothe front brakes 88, and where the first front brake pressure is equalto the second rear brake pressure (i.e. the brake pressures applied bythe master cylinders 92, 112 in both scenarios are the same), the firstfront brake pressure is greater than the second front brake pressure;the second rear brake pressure is greater than the first rear brakepressure; and the second front rear brake pressure is greater than thefirst rear brake pressure. As such for equal amounts of brake pressureapplied by the master cylinders 92, 112, the pump will apply more brakepressure when the foot brake lever 110 is actuated than when the handbrake lever 90 is actuated.

Although the driver of the ATV 9 may actuate the hand brake lever 90 andthe foot brake lever 110 individually, the driver may sometimes actuateboth brake levers 90, 110 at the same time. In such a scenario, shouldthe rear brake pressure applied to the rear brake 102 by the rear mastercylinder 112 be less than would have be applied by the pump 154 had onlythe hand brake lever 90 been actuated such that the front mastercylinder 92 would be applying the same front brake pressure, then theelectronic controller 156 actuates the pump 154 to boost the rear brakepressure. Similarly, should the front brake pressure applied to thefront brakes 88 by the front master cylinder 92 be less than would havebeen applied by the pump 154 had only the foot brake lever 100 beenactuated such that the rear master cylinder 112 would be applying thesame rear brake pressure, then the electronic controller 156 actuatesthe pump 154 to boost the front brake pressure.

Under some operating conditions, the electronic brake control unit 124may control the pump 154 and/or the valves 164 a, 164 b, 164 c to: applymore or less rear brake pressure to the rear brake 102 then describedabove when the hand brake lever 90 is actuated; apply more or less frontbrake pressure to the front brakes 88 then described above when the footbrake lever 110 is actuated; boost the front brake pressure applied tothe front brakes 88 by the front master cylinder 92 when the hand brakelever 90 is actuated; boost the rear brake pressure applied to the rearbrake 102 by the rear master cylinder 112 when the foot brake lever 110is actuated; apply different front brake pressures to the two frontbrakes 88; and apply a brake pressure to one or more of the brakes 88,102 even when none of the brake levers 90, 110 is actuated. Anon-limiting example is provided further below.

The operation of the ABS will now be described. During operation, theABS uses wheel speed signals received by the electronic controller 156from three wheel speed sensors 180 (schematically illustrated in FIG.11) that detect the speed of rotations of the three wheels 18. Theelectronic controller 156 detects the onset of locking (or actuallocking) of one of the front left and right brakes 88, or the onset oflocking (or actual locking) of the rear brake 102, when one of the wheelspeed sensors 180 reports a significantly lower wheel speed than theother speed sensors 180. When this happens, the electronic controller156 causes the valve 164 a, 164 b, 164 c connected to the brake 88 or102 that is locked or about to become locked to modulate the pressureapplied by the corresponding caliper 84 or 108 on the disc 82 or 106, byrepeatedly closing and opening the valve 164 a, 164 b or 164 c torepeatedly reduce or release and then re-apply brake pressure in thecorresponding brake line 95L, 95R or 116 until the wheel 18 connected tothe brake 88 or 102 that was locked or about to become locked rotatesagain at about the same speed as the other wheels 18. As such, theelectronic controller 156 controls operation of the valves 164 a, 164 band 164 c by opening and closing them cyclically for preventing lockingof the front right brake 88, the front left brake 88 and the rear brake102 respectively. It is contemplated that this control could be appliedto two or all of the brakes 88, 102 at the same time.

It is also contemplated that, in the four-wheel drive mode, theelectronic controller 156 may detect a loss of traction of one of thefront wheels 18. In such a scenario, one of the two front speed sensors180 reports a significantly higher speed than the other one of the twofront speed sensors 180 when the corresponding front left or right wheel18 is slipping. In response, the electronic controller 156 may causebrake pressure to be applied to the brake 88 that corresponds to theslipping front wheel 18 by opening the corresponding valve 164 a or 164b and actuating the pump 154. This action causes the front differential76 to transfer torque to the slower one of the front wheels 18. As inthe case of ABS operation, the electronic controller 156 may modulatethe brake pressure applied to the brake 88 of the slipping front wheel18, by repeatedly closing and opening the valve 164 a or 164 b torepeatedly reduce or release and then re-apply brake pressure in thecorresponding brake line 95L, 95R until the front wheel 18 that wasslipping gains traction and starts rotating again at about the samespeed as the other front wheel 18.

It is contemplate that the electronic control unit 124 could also useinputs from one or more operating condition sensors, such as the vehicleacceleration sensor 182 schematically shown in FIG. 11, for sensing oneor more corresponding operating conditions of the ATV 9. The one or moreoperating condition sensors are electronically connected to theelectronic controller 156 for sending one or more correspondingoperating condition signals to the electronic controller 156.

FIG. 12 schematically represent the ABS assembly of the embodiment ofFIG. 8. The ABS assembly of FIG. 12 is the same as the one illustratedin FIG. 11 except that a valve 164 d for opening and closing the outlet162 d and wheel speed sensor 180 have been added. The valve 164 d andthe wheel speed sensor are electronically connected to the electroniccontroller 156. The electronic controller 156 controls the opening andclosing of the valve 164 d to control the brake pressure applied to therear left brake 102 in the same way as the valve 164 c is controlled tocontrol the brake pressure applied to the rear right brake 102. Inaddition, since in the embodiment of FIG. 8 the rear wheels 18 canrotate at different speeds, slipping of the rear wheels can becontrolled using the valves 164 c, 164 d and the pump 154 in the sameway as described above to control slipping of the front wheels 18 usingthe valves 164 a, 164 b and the pump 154.

It is contemplated that the above described braking assemblies could beused with electronic brake control units that provide braking systemsthat provide braking functions other than or in addition to those of anABS.

Modifications and improvements to the above-described embodiments of thepresent technology may become apparent to those skilled in the art. Theforegoing description is intended to be exemplary rather than limiting.The scope of the present technology is therefore intended to be limitedsolely by the scope of the appended claims.

What is claimed is:
 1. A vehicle comprising: a frame; a straddle seatmounted to the frame; a front right wheel operatively connected to theframe; a front left wheel operatively connected to the frame; a rearwheel operatively connected to the frame; a steering assemblyoperatively connected to the front left and right wheels; a motormounted to the frame for providing power to at least one of the wheels;a front right brake operatively connected to the front right wheel forbraking the front right wheel; a front left brake operatively connectedto the front left wheel for braking the front left wheel; a rear brakeoperatively connected to the rear wheel for braking the rear wheel; anelectronic brake control unit comprising: a pump; a valve box fluidlyconnected to the pump, the valve box comprising: a first inlet; a firstoutlet fluidly connected to the front right brake; a second outletfluidly connected to the front left brake; a first valve selectivelyfluidly connecting the first inlet and the pump with the first outlet; asecond valve selectively fluidly connecting the first inlet and the pumpwith the second outlet; a second inlet; a third outlet fluidly connectedto the rear brake; and a third valve selectively fluidly connecting thesecond inlet and the pump with the third outlet; a first pressure sensordisposed in the valve box for sensing a first fluid pressure between thefirst inlet and the first and second valves; and an electroniccontroller electronically connected to the pump, the first valve, thesecond valve and the third valve for controlling operation of the pump,the first valve, the second valve and the third valve, andelectronically connected to the first pressure sensor for receiving afirst signal indicative of the first fluid pressure sensed by the firstpressure sensor; a first master cylinder fluidly connected to the firstinlet; a hand brake lever operatively connected to the first mastercylinder for actuating the first master cylinder and thereby actuate thefront right and left brakes through the valve box; a second mastercylinder fluidly connected to the second inlet; a foot brake leveroperatively connected to the second master cylinder for actuating thesecond master cylinder and thereby actuate the rear brake through thevalve box; a second pressure sensor disposed externally of the valvebox, the second pressure sensor sensing fluid pressure between thesecond inlet and the second master cylinder, the second pressure sensorbeing electronically connected to the electronic controller for sendinga second signal indicative of the second fluid pressure sensed by thesecond pressure sensor, the electronic brake control unit selectivelyactuating the rear brake in response to actuation of the first mastercylinder by opening the third valve and by actuating the pump, theelectronic brake control unit selectively actuating the front right andleft brakes in response to actuation of the second master cylinder byopening the first and second valves and by actuating the pump.
 2. Thevehicle of claim 1, wherein the second pressure sensor is mounted to thesecond master cylinder.
 3. The vehicle of claim 2, wherein the secondpressure sensor is vertically higher than the foot brake lever.
 4. Thevehicle of claim 1, wherein: the rear wheel is a rear right wheel; thevehicle further comprises a rear left wheel operatively connected to theframe; and the rear brake is operatively connected to the rear right andleft wheels for braking the rear right and left wheels.
 5. The vehicleof claim 1, wherein: the rear wheel is a rear right wheel; and the rearbrake is a rear right brake; the vehicle further comprises: a rear leftwheel operatively connected to the frame; and a rear left brakeoperatively connected to the rear left wheel for braking the rear leftwheel; the valve box further comprises: a fourth outlet fluidlyconnected to the rear left brake; and a fourth valve selectively fluidlyconnecting the second inlet and the pump with the fourth outlet; andwherein: the electronic controller is electronically connected to thefourth valve for controlling operation of the fourth valve; the footbrake lever is operatively connected to the second master cylinder foractuating the second master cylinder and thereby actuate the rear rightand left brakes through the valve box; and the electronic brake controlunit selectively actuates the rear left and right brakes in response toactuation of the first master cylinder by opening the third and fourthvalves and by actuating the pump.
 6. The vehicle of claim 1, wherein:the electronic brake control unit selectively actuates the rear brake inresponse to actuation of the first master cylinder by opening the thirdvalve and by actuating the pump only when the first pressure sensed bythe first pressure sensor is above a first pressure threshold, theelectronic brake control unit selectively actuating the front right andleft brakes in response to actuation of the second master cylinder byopening the first and second valves and by actuating the pump only whenthe second pressure sensed by the second pressure sensor is above asecond pressure threshold; and the second pressure threshold is greaterthan the first pressure threshold.
 7. The vehicle of claim 6, whereinthe first pressure threshold is less than 0.5 psi.
 8. The vehicle ofclaim 7, wherein the first pressure threshold is 0 psi.
 9. The vehicleof claim 7, wherein the second pressure threshold is 5 psi.
 10. Thevehicle of claim 6, wherein the second pressure threshold is 5 psi. 11.The vehicle of claim 1, wherein: when the electronic brake control unitactuates the rear brake in response to actuation of the first mastercylinder by opening the third valve and by actuating the pump: the firstmaster cylinder applies a first front brake pressure to the front rightand left brakes; and the pump applies a first rear brake pressure to therear brake; when the electronic brake control unit actuates the frontright and left brakes in response to actuation of the second mastercylinder by opening the first and second valves and by actuating thepump: the pump applies a second front brake pressure to the front rightand left brakes; and the second master cylinder applies a second rearbrake pressure to the rear brake; and the first front brake pressure isgreater than the first rear brake pressure.
 12. The vehicle of claim 11,wherein the second rear brake pressure is greater than the second frontbrake pressure.
 13. The vehicle of claim 11, wherein, for equal firstfront brake pressure and second rear brake pressure, the first frontbrake pressure is greater than the second front brake pressure.
 14. Thevehicle of claim 11, wherein, for equal first front brake pressure andsecond rear brake pressure, the second rear brake pressure is greaterthan the first rear brake pressure.
 15. The vehicle of claim 11,wherein: a front-to-rear braking ratio corresponds to the first frontbrake pressure divided by the first rear brake pressure; a rear-to-frontbraking ratio correspond to the second rear brake pressure divided bythe second front brake pressure; and the front-to-rear braking ratio isgreater than the rear-to-front braking ratio.
 16. The vehicle of claim1, further comprising: a first inlet brake line fluidly connecting thefirst master cylinder to the first inlet; a second inlet brake linefluidly connecting the second master cylinder to the second inlet; afirst outlet brake line fluidly connecting the front right brake to thefirst outlet; a second outlet brake line fluidly connecting the frontleft brake to the second outlet; and a third outlet brake line fluidlyconnecting the rear brake to the third outlet.
 17. The vehicle of claim1, wherein the electronic controller controls operation of the firstvalve, the second valve and the third valve by opening and closing ofthe first valve, the second valve and the third valve cyclically forpreventing locking of the front right brake, the front left brake andthe rear brake respectively.
 18. The vehicle of claim 1, furthercomprising a brake fluid reservoir spaced from and fluidly connected tothe second master cylinder.